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Biomedical subjects

L Yu

Publications and source records attributed to L Yu.

At least 523 records · Page 29Linked to original sources
PubMed1996

[Labeling of antihuman bladder carcinoma monoclonal antibody with a technetium-99m and radioimmunoimaging of human bladder carcinoma xenograft in nude mice].

Anti-human bladder carcinoma cell line BIU-87 monoclonal antibody-BDI-1 was labeled with 99mTc by direct mercaptoethanol reducing method. Quality control tests showed that the labeling yield was 69.9%; the radiochemical purity was higher than 90%; the immunoreactive fraction of 99mTc-BDI-1 was 81% and the association constant was 1.22 x 10(-9) M-1. The radioimmunoimaging of human bladder carcinoma xenograft in nude mice and the biodistribution of 99mTc-BDI-1 were studied. After having been scintigraphed at three time intervals (at 4, 16 and 22 hour), the animals were sacrificed for biodistribution of 99mTc-BDI-1. Tumor can be seen clearly at 22 hour after intravenous injection of 99mTc-BDI-1; %ID/g (percentage of the injected dose per gram of tissue) of tumor was 20.70, the average T/NT was 10.52, the minimum T/NT was 2.90 (tumor/kidney) and the maximum T/NT was 20.70 (tumor/small intestine or muscule). The results above indicated that 99mTc-BDI-1 can be used for radioimmunodetection of human bladder carcinoma in vivo and BDI-1 may be suitable as a targeting device in patients.

Animals↗
PubMed1996

[Amplification, cloning and sequence analysis of the variable region genes of monoclonal antibody against human bladder carcinoma].

We have designed two sets of oligonucleotide primers to amplify the immunoglobulin heavy- and light-chain variable region genes from genomic DNA by the polymerase chain reaction, PCR. The genomic DNA was extracted from hybridoma BDI-1 cell, which secrets a monoclonal antibody against human bladder carcinoma. The primers contain special restriction sites that allow the variable region genes to be easy to cloning for sequencing and expression. The PCR products were ligated to plasmid PUC19. The recombinants were sequenced with Sanger's method. It was proved that a full-length VH and V kappa genes was 366 and 324 base pairs respectively. Comparaing with other published sequences, the VH gene was a member of mouse heavy-chain VH subgroup II and originated from rearrangement of VH, Dsp2.2 and JH4; the V kappa gene was V kappa subgroup IV and from V kappa and J kappa 4. It was suggested that obtained VH and V kappa genes were potentially functional genes of the monoclonal antibody against human bladder carcinoma.

Antibodies, Monoclonal↗
PubMed1996

[IL-6 gene expression in human tumor cell lines].

Using Northern blot techniques and IL-6-dependent cell line proliferating response method, the IL-6 gene expression in 8 sorts of human tumor cell lines and the IL-6 biologic activity in 5 sorts of medium were investigated. The results revealed that IL-6mRNA was positively expressed in 7 sorts of these cell lines and there were differential IL-6 biologic activity in 5 sorts of assayed medium. These results may providea basis for further research.

Blotting, Northern↗
PubMed1996

[The antitumor activity of elemene is associated with apoptosis].

Elemene, isolated from the Chinese medicinal herb Rhizoma Zedoariae was shown to exhibit antitumor activity in vitro and in vivo to human and murine tumor cells. This novel antineoplastic agent has been demonstrated to have substantial clinical activity against various tumors. In this paper, the mechanisms of antitumor activity of elemene are reported. The in vitro effect of elemene on the growth of leukemia cells was evaluated by MTT assay. The IC50 values of elemene for promyelocytic leukemia HL-60 cells and erythroleukemia K562 cells were found to be 27.5 micrograms/ml and 81 micrograms/ml, respectively, while IC50 for peripheral blood leukocytes (PBL) was 254.3 micrograms/ml. The inhibitory effect of elemene on proliferation of HL-60 cells was associated with cell cycle arrest from, S to G2M phase transition and with induction of apoptosis. The apoptosis of tumor cells was confirmed by DNA ladder formation on gel electrophoresis and characteristic ultrastructural alternations. These results indicate that induction of apoptosis contributes to the mechanisms for antitumor activity of elemene.

Antineoplastic Agents, Phytogenic↗
PubMed1996

[Growth inhibitory effect of retinoic acid in human breast cancer cells correlates with retinoic acid receptor alpha (RAR alpha) expression].

The relationship between the effect of retinoic acid (RA) on the growth of breast cancer cell and their estrogen receptor (ER) status as well as the relationship between RA effect and the expression of retinoic acid receptorsd (RAR alpha) were studied by cell growth assay, Northern Blot and gene transfection. It was found that RA could only inhibit the growth of ER-positive but not ER-negative breast cancer cells. RAR alpha mRNA level was significantly higher in ER-positive breast cancer cell lines than that in ER-negative breast cancer cell line. The expressions of other subtypes of RAR in ER-positive cells were not significantly different from those in ER-negative ones. When, RAR alpha cDNA was introduced and ixpressed in RA-resistant, ER-negative MDA-MB-231 breast cancer cell line, its growth was strongly inhibited by RA. These results indicate that RAR alpha plays a major role in the retinoi-dmediated inhibition of growth in human breast cancer cells.

Antineoplastic Agents↗
PubMed1996

Inhibition of spontaneous apoptosis in human breast cancer.

Breast tumorigenesis proceeds through an accumulation of specific genetic alteration. Breast malignant transformation is dependent on not only the rate of cell production but also on apoptosis, a genetically programed process of autonomous cell death. We investigated whether breast tumorigenesis involved an altered susceptibility to apoptosis and proliferation by examining normal breast epithelium and breast cancer samples. We found there is a great inhibition of spontaneous apoptosis in breast cancer cells compared with normal breast epithelium. The inhibition of apoptosis in breast cancer may contribute to neoplastic transformation.

Apoptosis↗
PubMed1996

Retinoic acid nuclear receptor alpha(RAR alpha) plays a major role in retinoid-mediated inhibition of growth in human breast carcinoma cells.

Retinoids mediate their actions via retinoic acid receptors (RARs) and retinoid X receptors (RXRs). Each of class of these nuclear retinoid receptor is further subdivided into three species namely alpha, beta and gamma. Recently studies demonstrated that estrogen receptor (ER)-positive human breast cancer (HBC) cell lines are sensitive and ER-negative cell lines are resistant to growth inhibitory effects of retinoic acid (RA). In this study, we found that only RAR alpha mRNA levels was strongly correlated with ER-status. To further investigate the major role of RAR alpha in retinoid-mediated inhibition of growth, we transfected RAR alpha cDNA into two RA-resistant ER-negative HBC cell lines. Analysis of different clonal populations of RAR alpha transfectants from each cell line revealed growth inhibition by retinoids. Our results demonstrated that RAR alpha plays a major role in mediating retinoids inhibition of growth in HBC cells and adequate levels of RAR alpha are required for such an effect.

Breast Neoplasms↗
PubMed1996

[Corneal endothelial decompensation of iridocorneal endothelial syndrome treated by penetrating keratoplasty].

OBJECTIVE: To evaluate the effect of penetrating keratoplasty in treatment of iridocorneal endothelial syndrome. METHODS: The clinical and pathologic evaluation records were retrospectively analyzed for 8 cases with iridocorneal endothelial syndrome treated by penetrating keratoplasty. Postoperatively, they were followed for 3 months to 6 years. RESULTS: Seven cases had visual improvement, five buttons kept being transparent and three buttons became opaque. CONCLUSIONS: The penetrating keratoplasty is an effective measure for treatment of corneal endothelial decompensation of iridocorneal endothelial syndrome. However, the successful operative rate of this syndrome is lower than that in cases with corneal leucoma without vascularization.

Adult↗
PubMed1996

[Vestibular and auditory functions in Ménière's disease].

This paper is, aiming at understanding disturbances of and correllation between colchear and vestibular functions in Meniere's disease. Auditory and vestibular functions in 121 Meniere cases (70 males and 51 females, age ranging from 19 to 63 years), diagnosed according to the AAO-HNS criteria, were analysed. The results were as follows: 1)There was positive correlation between semicircular canal paresis and hearing impairment. 2) There was statistically significant positive correlation between hearing impairment and the -SP/AP ratio. 3) There was statistically significant correlation between hearing impairment and glycerin test result, the rate of positive result being higher in those with advanced hearing loss than in those with mild loss. 4) There was correlation between the rate of positive glycerin test result and audiogram configuration. The rate with rising audiogram pattern was higher than with that falling pattern (69.0% vs 33.3%). It was also found that ECochG was far more effective than glycerin test in diagnosing Meniere's disease. The physiologic basis and significance of ECochG and glycerin test in Meniere's disease were discussed.

Adult↗
PubMed1995

The involvement of threonine 160 of cytochrome b of Rhodobacter sphaeroides cytochrome bc1 complex in quinone binding and interaction with subunit IV.

The cytochrome b subunit (subunit I) of the ubiquinolcytochrome c reductase (bc1 complex) is thought to participate in the formation of two quinone/quinol reaction centers, an oxidizing center (Qo) and a reducing center, in accordance with the quinone cycle mechanism. Threonine 160 is a highly conserved residue in a segment of subunit I that was shown to bind quinone and is placed near the putative Qo site in current models of the bc1 complex. Rhodobacter sphaeroides cells expressing bc1 complexes with Ser or Tyr substituted for Thr160 grow photosynthetically at a reduced rate, and cells expressing the mutated complexes produce an "elevated" level of the bc1 complex. The Ser substitution also affects the interaction of subunit IV with subunit I. Replacement of Thr160 by Ser results in about a 70% loss of the activity in the purified complex, whereas substitution by Tyr lowers the activity by more than 80%. Both replacements lower the apparent Km for ubiquinol. Electron paramagnetic resonance (EPR) spectroscopy shows that in the Ser substituted complex, the environments of the Rieske iron-sulfur cluster in subunit III and the high potential cytochrome b (b562) in subunit I have been modified. The spectra of the Ser160 and Tyr160 iron-sulfur clusters have become redox-insensitive, with a line shape resembling that of the native complex in the fully reduced state. The EPR signal of b562 in the Ser160 complex is shifted from g = 3.50 to g = 3.52, but otherwise the line shape is very similar to the spectrum of the native complex. Most of these results are consistent with current ideas regarding the structure and function of Qo in the bc1 complex, except for the alteration of the b562 EPR feature, because this heme is not thought to be located in proximity to Qo. Immunoblotting analysis showed that the Ser or Tyr substituted complex contained significantly less than a stoichiometric amount of subunit IV. The enzymatic activity of mutated bc1 complex was found to be activable by the addition of purified subunit IV. These results indicate that Thr160 plays an important role in the structure and/or function of the bc1 complex.

Antimycin A↗
PubMed1995

Modified ligands to FA and FB in photosystem I. II. Characterization of a mixed ligand [4Fe-4S] cluster in the C51D mutant of PsaC upon rebinding to P700-Fx cores.

A Photosystem I (PS I) complex reconstituted with PsaC-C51D (aspartate in lieu of cysteine in position 51) shows light-induced EPR signals with g values, line widths, and photoreduction behavior characteristic of FB. Contrary to an earlier report, a [3Fe-4S] cluster was not located in the reconstituted PS I complex. Instead, a second set of resonances with g values of 2.044, 1.942, and 1.853 becomes EPR-visible when the C51D-PS I complex is measured at 4.2 K. This fast relaxing center, termed FA' is likely to represent a [4Fe-4S] cluster in the mixed ligand (3Cys.1Asp) site. Redox studies show that the Em of FA' and FB are -630 mV and -575 mV, respectively. Room temperature optical studies support the presence of two functioning electron acceptors subsequent to Fx, and NADP+ photoreduction rates mediated by ferredoxin and flavodoxin are nearly equivalent to the wild type. In addition to [3Fe-4S] clusters and S = 1/2 ground state [4Fe-4S] clusters, the free PsaC-C51D protein shows resonances near g = 5.5, which may represent a population of high spin (S = 3/2) [4Fe-4S] clusters in the mixed ligand FA' site. Similar to the C14D-PS I mutant complex, it is proposed that the P700-Fx core selectively rebinds those free PsaC-C51D proteins that contain two [4Fe-4S] clusters. These studies show that primary photochemistry and electron transfer rates in PS I are relatively unaffected by the presence of a highly reducing, mixed ligand cluster in the FA' site.

Aspartic Acid↗
PubMed1995

Mu opioid receptor gene expression in immune cells.

We have previously demonstrated that administering morphine sulfate to rhesus monkeys alters the cell-mediated as well as humoral immune responses of these primates. Furthermore, morphine treatment greatly reduces the chemotactic and phagocytotic activities of primate polymorphonuclear (PMN) cells. The present study describes the identification and isolation of mRNA encoding the mu opioid receptor gene sequence from human and monkey immune cells. Through the use of primer sequences designed from the human brain mu opioid receptor cDNA sequence, specific opioid receptor segments in mRNA transcripts were amplified, cloned, and sequenced. The mu opioid receptor gene was therefore found expressed in the following cell types: CEM x174 (a hybrid of human T and B cells), Raji (human B cells), human CD4+ cells, human monocytes/macrophages, human PMN, monkey peripheral blood mononuclear cells (PBMC), and monkey PMN. These studies present the first evidence to demonstrate that cells of human and monkey immune systems constitutively express mu opioid receptor mRNA.

Amino Acid Sequence↗
PubMed1995

Alteration of OBCAM conformation as a result of opioid receptor expression and opioid ligand treatment.

Several lines of evidence link the opioid binding cell adhesion molecule (OBCAM) to opioid function. When delta-opioid receptor cDNA (DOR-1) was expressed in CHO cells, OBCAM immunoreactivity (OBCAM-ir) was detected. Transfected cell lines which displayed high opioid binding also expressed high cell surface OBCAM-ir, while untransfected CHO and vector control cells did not. The positive control, neural cell adhesion molecule (NCAM), a protein with structural homology to OBCAM, displayed the same levels of immunofluorescence in transfected and nontransfected cell lines. Membranes from CHO cells transfected with and expressing a variety of muscarinic and dopamine receptors were tested for immunoreactivity. No significant OBCAM-ir was detected in any of these cell membranes. When anti-OBCAM peptide antibodies were used for immunoblots of CHO cells, untransfected, non-binding transfected, and high binding transfected cells revealed the same banding patterns with approximately equal intensity. These observations suggest that in untransfected cells OBCAM is either not present on the extracellular side of the CHO cell membrane or that it exists in an altered conformation which changes upon transfection with opioid receptors to allow recognition of the non-denatured protein by anti-OBCAM antibodies.

Animals↗
PubMed1995

Cloning, gene sequencing, and expression of the small molecular mass ubiquinone-binding protein of mitochondrial ubiquinol-cytochrome c reductase.

The cDNA encoding QPc-9.5 kDa (subunit VII) of bovine heart mitochondrial ubiquinol-cytochrome c reductase was cloned and sequenced. This cDNA is 665 base pairs long with an open reading frame of 246 base pairs that encodes an 81-amino acid mature QPc-9.5 kDa. The insert contains 395 base pairs of a 3'-noncoding sequence with a poly(A) tail. The amino acid sequence of QPc-9.5 kDa deduced from this nucleotide sequence is the same as that obtained by protein sequencing except that residue 61 is tryptophan instead of cysteine. The QPc-9.5 kDa was overexpressed in Escherichia coli JM109 cells as a glutathione S-transferase fusion protein (GST-QPc) using the expression vector, pGEX/QPc. The yield of soluble active recombinant GST-QPc fusion protein depends on the induction growth time, temperature, and medium. Maximum yield of recombinant fusion protein was obtained from cells harvested 3 h postinduction of growth at 27 degrees C on LB medium containing betaine and sorbitol. QPc-9.5 kDa was released from the fusion protein by proteolytic cleavage with thrombin. Isolated recombinant QPc-9.5 kDa showed one protein band in SDS-polyacrylamide gel electrophroesis corresponding to subunit VII of mitochondrial ubiquinol-cytochrome c reductase. Although the isolated recombinant QPc-9.5 kDa is soluble in aqueous solution, it is in a highly aggregated form, with an apparent molecular mass of over 1 million. Addition of detergent deaggreates the isolated protein to the monomeric state, suggesting that the recombinant protein exists as a hydrophobic aggregation in aqueous solution. The recombinant QPc-9.5 kDa binds ubiquinone and shows a spectral blue shift. Upon titration of the recombinant protein with ubiquinone, a saturation behavior is observed, suggesting that the binding is specific and that the recombinant protein may be in the functionally active state.

Amino Acid Sequence↗
PubMed1995

Identification of dynorphins as endogenous ligands for an opioid receptor-like orphan receptor.

To identify the endogenous ligands for a cloned orphan receptor that shares high degrees of sequence homology with opioid receptors, this orphan receptor was expressed in Xenopus oocytes and in mammalian cell lines CHO-K1 and HEK-293. The coupling of the receptor to a G protein-activated K+ channel was used as a functional assay in oocytes. Endogenous opioid peptide dynorphins were found to activate the K+ channel by stimulating the orphan receptor. This activation was dose-dependent, with EC50 values at 45 and 37 nM for dynorphin A and dynorphin A-(1-13), respectively. The dynorphin effect was antagonized by the non-selective opioid antagonist naloxone but at rather high concentrations in the micromolar range. Naloxone also caused a rightward shift of the dose-response curve for dynorphin A, suggesting a competitive antagonism mechanism. In transiently transfected cells, 5 microM dynorphin A-(1-13) inhibited the forskolin-stimulated cyclic AMP increase by 51 and 35% in CHO-K1 and HEK-293 cells, respectively. Other classes of endogenous opioids, i.e. enkephalins and endorphins, caused very little activation of this receptor. These results suggest that this orphan receptor is a member of the opioid receptor family and that dynorphins are endogenous ligands for this receptor.

Animals↗
PubMed1995

Characterization of irreversible binding of beta-funaltrexamine to the cloned rat mu opioid receptor.

Binding of beta-funaltrexamine (beta-FNA) to the cloned rat mu opioid receptor expressed in COS-1 cells or Chinese hamster ovary cells was examined. beta-FNA bound to the mu receptor with high affinity. Irreversible binding of [3H]beta-FNA was defined as the binding that could not be dissociated by trichloroacetic acid. Na+ greatly enhanced the specific irreversible binding of [3H]beta-FNA to the mu receptor, which was concentration- and time-dependent. Specific irreversible binding of [3H]beta-FNA was potently inhibited by CTAP (a mu ligand), but not by ICI174,864 (a delta ligand) or U50,488H (a kappa ligand). These results indicate that [3H]beta-FNA binds irreversibly to the cloned mu opioid receptor. SDS-polyacrylamide gel electrophoresis and fluorography showed that [3H]beta-FNA-labeled receptors migrated as one broad and diffuse band with a mass of 80 kDa in Chinese hamster ovary or COS cells and as one band with a mass of 67 kDa in the rat brain preparation. Upon removal of N-linked carbohydrates, labeled receptors became a sharper band with a mass of approximately 40 kDa. [3H]beta-FNA did not bind irreversibly to the cloned rat kappa receptor. [3H]beta-FNA binding to four chimeric mu/kappa receptors was examined. The region from the middle of the third intracellular loop to the C terminus of the mu receptor is necessary for irreversible binding of beta-FNA.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗